I bought the ball to sit on while I work on the computer. (1.70 height requires 75cm, not smaller because it won't reach the desk) I am very satisfied as its material is somewhat softer than another one I have of the brand Amilla. If you are experiencing sciatica problems and feel pain when sitting, choose this one. I'm just not sure if the included foot pump works... I inflated it with an Amilla hand pump.

Very good product, I have bought it many times.
I use it as a computer chair, for my students.